Transmyocardial laser revascularisation in acutely ischaemic myocardium1

Mueller, Xavier M.; Tevaearai, H. T.; Genton, Claude Yves; Béttex, Dominique; Segesser, Ludwig K. von

doi:10.1016/s1010-7940(97)00308-4

Cited by 16 publications

(4 citation statements)

References 19 publications

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“…Although the exact mechanism of TMLR is unknown, improved perfusion and relief of symptoms after treatment could result from patent (open) tunnels created by the laser or from laser-induced angiogenesis. While some studies have found evidence of tunnel patency and of angiogenesis (Frazier, March & Horvath 1999 and references therein; Kadipasaoglu et al 1997;Berwing et al 1997) others have failed to find such evidence (Hardy et al 1987;Landreneau et al 1991;Mueller et al 1998). Schofield et al (1999) found no evidence of improved cardiac function or myocardial perfusion, although they did find that the treatment provided relief from angina symptoms.…”

Section: Introductionmentioning

confidence: 99%

Solute uptake through the walls of a pulsating channel

Waters

2001

J. Fluid Mech.

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We investigate the uptake of a passive solute through the walls of a pulsating, fluid-filled channel into an adjacent medium in which the solute diffuses and is consumed at a constant rate. One end of the channel is open to well-mixed fluid containing the solute. The channel walls oscillate periodically in time and this prescribed motion generates steady streaming within the channel. We determine how this flow enhances the overall solute consumption (i.e. the flux of solute into the channel), the solute dispersion along the channel and the quantity of solute in the adjacent medium. The solute disperses in the channel due to the interaction between advection and transverse diffusion. The time-mean solute distribution throughout the channel and the medium is determined for a wide range of parameters. The results are applied to a new surgical technique used to treat patients with severe coronary artery disease, in which narrow tubes are created within ischemic heart muscle in an attempt to reperfuse the area directly with oxygenated blood.

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Section: Introductionmentioning

confidence: 99%

Solute uptake through the walls of a pulsating channel

Waters

2001

J. Fluid Mech.

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“…Whittaker et al [30,31] and others [32] found that TMLR does not increase myocardial blood flow in a region after ligature of a coronary artery, except if the channels were created 2 months before the coronary occlusion. A favorable effect of TMLR during acute myocardial infarction could also not be proven [33,34].…”

Section: Experimental Studies and Potential Mechanisms Of The Laser Ementioning

confidence: 95%

Transmyocardial Laser Revascularization: Established Procedure, Acupuncture of the Heart or Placebo Effect?

Eckstein¹,

Boss²,

Frenz

et al. 2001

Heart Drug

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Considering the nearly universal skepticism transmyocardial laser revascularization (TMLR) aroused a few years ago, the so-called snake heart procedure has come a long way. The notion that the human heart enjoys significant perfusion from a spongy underlay of microcapillaries and sinusoids has been embraced by hundreds of researchers who have poked away at the coronary bed with external and internal lasers, radiofrequency probes, rotary cutters and saline jets, as well as developing technologies for implanting angiogenic growth factors into and around the resultant channels. TMLR has been described as a therapeutic option for end-stage coronary artery disease when percutaneous transluminal angioplasty and surgical myocardial revascularization are no longer possible and transplantation is not indicated. While debate continues to rage among surgeons and interventionists over the best way to perform transmyocardial laser, a greater question looms over the field: how does it work? No one has been able to explain yet why the procedure works in some patients and utterly fails in others, or to convincingly substantiate the procedure’s contributions to myocardial reperfusion. A few investigators believe that the procedure’s secret lies in creating patent channels. However, mid- and long-term patency of laser-created channels seem not to be required for successful treatment as initially assumed. The development of new vessels within and around the scar following TMLR (a phenomenon called ‘neoangiogenesis’) has moved more and more to the center of attention during the last few years. Some form of angiogenesis or neovascularization around the channels is the most favored explanation now, but nobody knows how TMLR stimulates such processes or how to measure them effectively. Although prospective randomized studies have been able to demonstrate some effectiveness of this treatment, the exact mechanisms of laser revascularization are still not completely elucidated. The notion of mechanisms such as sympathetic myocardial denervation and induction of microinfarctions transforming ischemia into necrotic myocardium has been abandoned. As recently as 1996, the prospect of transmyocardial revascularization becoming a breakthrough therapy seemed exciting enough to the financial market that the stock of PLC Medical Systems, then the front-runner in the field, soared to USD 32 per share. But in only the 2nd year since receiving FDA approval, the company is now trading at around USD 1.5 a share and the laser sales have fallen below expectations. One problem may be that many hospitals do not switch on their TMLR lasers very often once they are installed, with usage estimates as low as one or two procedures per month in some centers.

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“…As with TMLR,14 the mechanisms of action during PMLR are unclear. Proposed laser mechanisms with insufficient and/or contradictory evidence include direct perfusion,15–18 microvascular angiogenesis,19–23 and cardiac afferent denervation 24–27. There is also insufficient evidence to support placebo effect13,28 and change in attitudes and expectations24 towards angina as significant factors in symptom relief.…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of percutaneous laser revascularization therapy for refractory angina

McGillion¹,

Cook²,

Victor³

et al. 2010

VHRM

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Refractory angina is a debilitating disease characterized by persistent cardiac pain resistant to all conventional treatments for coronary artery disease. Percutaneous myocardial laser revascularization (PMLR) has been proposed to improve symptoms in these patients. We used meta-analysis to assess the effectiveness of PMLR versus optimal medical therapy for improving angina symptoms, health-related quality of life (HRQL), and exercise performance; the impact on all-cause mortality was also examined. Seven trials, involving a total of 1,213 participants were included. Our primary analyses showed that at 12-month follow-up, those who had received PMLR had ≥2 Canadian Cardiovascular Society class angina symptom reductions, OR 2.13 (95% CI, 1.22 to 3.73), as well as improvements in aspects of HRQL including angina frequency, SMD = 0.29 (95% CI, 0.05 to 0.52), disease perception, SMD = 0.37 (95% CI, 0.14 to 0.61), and physical limitations, SMD = 0.29 (95% CI, 0.05 to 0.53). PMLR had no significant impact on all-cause mortality. Our secondary analyses, in which we considered data from one trial that featured a higher-dose laser group, yielded no significant overall impact of PMLR across outcomes. While PMLR may be effective for improving angina symptoms and related burden, further work is needed to clarify appropriate dose and impact on disease-specific mortality and adverse cardiac events.

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Transmyocardial laser revascularisation in acutely ischaemic myocardium1

Cited by 16 publications

References 19 publications

Solute uptake through the walls of a pulsating channel

Solute uptake through the walls of a pulsating channel

Transmyocardial Laser Revascularization: Established Procedure, Acupuncture of the Heart or Placebo Effect?

Effectiveness of percutaneous laser revascularization therapy for refractory angina

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